1. Field of the Invention
The present invention relates to a method and apparatus for processing substrates. Specifically, the invention relates to processing systems.
2. Background of the Related Art
Semiconductor processing typically involves the deposition and/or removal (etching) of materials from a substrate. Frequently, semiconductor processes require a vacuum environment. As a result, processing systems generally include a vacuum chamber coupled to a pumping system. The pumping system includes a vacuum pump which, when in communication with the chamber, can reduce the pressure of the enclosure defined by the vacuum chamber.
FIG. 1 is a schematic drawing of a typical processing system 100. The processing system 100 generally includes a chamber 102 having a dome-shaped top 103, a pumping module 104 and a gas delivery module 112. An opening 106 formed in the chamber body allows fluid communication between the chamber 102 and the pumping module 104. A support member 108 is disposed in the chamber 102 and provides a substrate receiving surface 110 adapted to support a substrate 111 during processing. The gas delivery module 112 is coupled to the chamber 102 via supply lines 113 and provides one or more gases to the chamber 102 during processing. A plasma generating assembly comprising a coil 115 disposed on the top 103 and a power supply 117 connected to the coil 115 is provided to generate a plasma in the chamber 102. Although not shown, the processing system 100 may include additional components known in the art such as sensors, motors, etc.
The processing system 100 is adaptable to plasma processing including etching and chemical vapor deposition (CVD). In the case of etching, etching gases are introduced into the chamber 102 and a plasma is struck by flowing a current through the coil 115. The reactive species in the plasma then etch the exposed portion of the metal, dielectric, or semiconductive material on the substrate 111. In order to maintain a desired pressure in the chamber 102, as well as remove gaseous by-products, the chamber 102 and the pumping module 104 are communicated via the opening 106. The resulting flow pattern of gases in the chamber 102 is shown by arrows 120.
One problem with conventional chambers is the non-symmetric flow of gases over the substrate being processed. Flow symmetry is important in order to ensure uniform deposition or removal of material from the substrate. The arrows 120 in FIG. 1 illustrate the non-uniform flow pattern within the chamber 102. In the case of an etching chamber for example, such a flow pattern results in a non-uniform etch rate of material from the substrate.
Another problem with conventional chambers, including etch chambers, is the potential for contamination of substrates being processed. During processing, material etched from the substrate or deposition gases introduced in the chamber deposit on the chamber surfaces and form a film thereon. Over time, such films may crack or chip under the influence of thermal stresses and gravitational forces. Portions of the film may then flake and deposit on the substrate resulting in defective devices. Issues of substrate contamination are typically addressed by periodically cleaning the chamber. For example, one or more cleaning gases may be flowed into the chamber to remove deposition from the chamber surfaces. The cleaning gases react with the deposited material to form gaseous by-products that can then be removed from the chamber by a pumping mechanism. The frequency at which a chamber is cleaned is typically referred to as the mean-wafer-between-clean (MWBC). Depending on the particular process being run in the chamber, the MWBC may be less than about one thousand wafers resulting in a significant detrimental impact on the overall throughput of the system.
One solution to the problem of contamination is to control the temperature of the chamber. Temperature control mitigates the thermal stresses that can lead to flaking and contamination. Accordingly, some processing systems, such as the one shown in FIG. 1, include a temperature control unit 124. The temperature control unit 124 in FIG. 1 is disposed around the dome 103 because deposition is typically increased on the inner surface of the dome 103. However, even where cooling units are used, particles are still generated in the chamber. Thus, conventional chambers continue to experience significant contamination of substrates. Further, temperature control units are expensive, both in the purchase price and the cost of operation. Additionally, the temperature control units typically occupy a large volume, thereby greatly increasing the amount of space needed for the processing system.
Another problem with conventional chambers is their lack of serviceability. For example, chambers are often coated with a material to prevent corrosion of chamber surfaces. The coating apparatus is typically an automated device with a pressurized fluid source and a spray nozzle. The coating apparatus is robotically actuated vertically along a central axis while simultaneously being rotated about the axis. However, due to their complex design, the chambers are not easily accessible to an automated coating apparatus. As a result, the surfaces are unevenly coated or, in some cases, not coated at all. For example, the chamber 102 typically consists of a manifold or plenum having an exhaust channel (e.g., the opening 106) formed therein. The exhaust channel extends outwardly from the body of the chamber 102 and is coupled at its end to the pumping module 104. Such an arrangement, wherein the surfaces lie along different planes and at different radii from a central axis, makes coating all surfaces of the chamber 102 with an automated device difficult.
Therefore, there is a need for a process chamber providing uniform flow of gases over a substrate while preferably mitigating the potential for contamination of the chamber and affording serviceability.
The present invention generally provides a method and apparatus for processing substrates. In one aspect of the invention, a processing system comprises a chamber having a top mounted pumping assembly. The chamber comprises a ceiling disposed on a chamber body and having an opening formed therein. The pumping assembly is connected to the ceiling and registered with the opening.
In another aspect of the invention, a chamber comprises a floor, a sidewall and an opening formed at an upper end of the chamber and a pumping assembly connected to the chamber and registered with the opening.
The chamber may further comprise a gas manifold disposed at an upper end of the chamber and defining an opening, an energy transmissive member disposed on the gas manifold, and a pumping assembly coupled to an upper end of the energy transmissive member.
In yet another aspect of the invention, an apparatus comprises a chamber body comprising a floor and a sidewall and defining an enclosure; a substrate support member disposed in the chamber body; a gas manifold disposed at an upper end of the chamber body; a fluid supply unit coupled to the gas manifold; an energy transmissive member disposed on the gas manifold and defining an opening at an upper end; a plasma generating assembly disposed about the energy transmissive member; and a pumping assembly coupled to the upper end of the energy transmissive member.
In still another aspect of the invention, a method for processing a substrate, comprises providing a chamber defining a processing region and having an opening formed at an upper end thereof; and evacuating the processing region through the opening.